feat(app): add error/loading boundaries and update dashboard routes

- Add error.tsx and loading.tsx boundaries for admin, parent, student, teacher routes

- Add dashboard-error-fallback and dashboard-loading-skeleton components

- Add student/learning page, parent/leave routes, teacher textbook components

- Update existing app routes across auth, dashboard, and API endpoints

- Update proxy middleware and next-auth type declarations

src/app/(dashboard)/parent/grades/error.tsx

@@ -0,0 +1,27 @@
+"use client"
+
+import { AlertCircle } from "lucide-react"
+
+import { EmptyState } from "@/shared/components/ui/empty-state"
+
+export default function ParentGradesError({
+  reset,
+}: {
+  error: Error & { digest?: string }
+  reset: () => void
+}) {
+  return (
+    <div className="flex h-full flex-col items-center justify-center space-y-4 p-8">
+      <EmptyState
+        icon={AlertCircle}
+        title="子女成绩页面加载失败"
+        description="抱歉，页面加载时发生了意外错误。请稍后重试。"
+        action={{
+          label: "重试",
+          onClick: () => reset(),
+        }}
+        className="border-none shadow-none h-auto"
+      />
+    </div>
+  )
+}

src/app/(dashboard)/parent/grades/loading.tsx

@@ -0,0 +1,32 @@
+import { Card, CardContent, CardHeader, CardTitle } from "@/shared/components/ui/card"
+import { Skeleton } from "@/shared/components/ui/skeleton"
+
+export default function Loading() {
+  return (
+    <div className="space-y-8 p-6 md:p-8">
+      <div className="space-y-2">
+        <Skeleton className="h-8 w-48" />
+        <Skeleton className="h-4 w-64" />
+      </div>
+      <div className="space-y-8">
+        {Array.from({ length: 2 }).map((_, i) => (
+          <Card key={i}>
+            <CardHeader>
+              <CardTitle className="text-lg">
+                <Skeleton className="h-5 w-32" />
+              </CardTitle>
+            </CardHeader>
+            <CardContent className="space-y-3">
+              <div className="grid grid-cols-2 gap-4 md:grid-cols-4">
+                {Array.from({ length: 4 }).map((_, j) => (
+                  <Skeleton key={j} className="h-20 w-full" />
+                ))}
+              </div>
+              <Skeleton className="h-40 w-full" />
+            </CardContent>
+          </Card>
+        ))}
+      </div>
+    </div>
+  )
+}

src/app/(dashboard)/parent/grades/page.tsx

@@ -1,16 +1,27 @@
-import { getAuthContext } from "@/shared/lib/auth-guard"
+import { requirePermission } from "@/shared/lib/auth-guard"
+import { Permissions } from "@/shared/types/permissions"
 import { getStudentGradeSummary } from "@/modules/grades/data-access"
+import { getClassAverageTrend } from "@/modules/grades/data-access-ranking"
 import { StudentGradeSummary } from "@/modules/grades/components/student-grade-summary"
+import { GradeTrendCard } from "@/modules/grades/components/grade-trend-card"
 import {
   ParentChildrenDataPage,
   ParentNoChildrenPage,
 } from "@/modules/parent/components/parent-children-data-page"
+import { ParentExportButton } from "@/modules/parent/components/parent-export-button"
 import { GraduationCap } from "lucide-react"
+import type { ClassAverageTrendResult } from "@/modules/grades/types"
 
 export const dynamic = "force-dynamic"
 
+interface ChildGradeItem {
+  studentId: string
+  summary: NonNullable<Awaited<ReturnType<typeof getStudentGradeSummary>>>
+  classAverageTrend: ClassAverageTrendResult | null
+}
+
 export default async function ParentGradesPage() {
-  const ctx = await getAuthContext()
+  const ctx = await requirePermission(Permissions.GRADE_RECORD_READ)
 
   if (ctx.dataScope.type !== "children" || ctx.dataScope.childrenIds.length === 0) {
     return (
@@ -26,26 +37,49 @@ export default async function ParentGradesPage() {
 
   // 使用 allSettled 容错：单个子女查询失败不影响其他子女展示
   const results = await Promise.allSettled(
-    ctx.dataScope.childrenIds.map((id) => getStudentGradeSummary(id)),
+    ctx.dataScope.childrenIds.map(async (id) => {
+      const [summary, classAverageTrend] = await Promise.all([
+        getStudentGradeSummary(id, ctx.dataScope),
+        // v3-P2-8：家长页面补齐趋势图，复用班级平均对比线
+        getClassAverageTrend(id, undefined, undefined, ctx.dataScope),
+      ])
+      return { summary, classAverageTrend, studentId: id }
+    }),
   )
-  const validSummaries = results
+  const validItems: ChildGradeItem[] = results
     .filter(
-      (r): r is PromiseFulfilledResult<NonNullable<Awaited<ReturnType<typeof getStudentGradeSummary>>>> =>
-        r.status === "fulfilled" && r.value !== null,
+      (
+        r,
+      ): r is PromiseFulfilledResult<{
+        summary: Awaited<ReturnType<typeof getStudentGradeSummary>>
+        classAverageTrend: ClassAverageTrendResult | null
+        studentId: string
+      }> => r.status === "fulfilled" && r.value.summary !== null,
     )
-    .map((r) => r.value)
+    .map((r) => ({
+      studentId: r.value.studentId,
+      summary: r.value.summary as NonNullable<typeof r.value.summary>,
+      classAverageTrend: r.value.classAverageTrend,
+    }))
 
   return (
     <ParentChildrenDataPage
       title="Children Grades"
-      description="View your children's grade records."
+      description="Compare grades across all your children. For single-child analysis, open the child's detail page."
       icon={GraduationCap}
       noRecordsTitle="No grade records"
       noRecordsDescription="Your children don't have any grade records yet."
-      items={validSummaries}
-      renderItem={(summary) => (
+      items={validItems}
+      renderItem={({ studentId, summary, classAverageTrend }) => (
         <>
-          <h3 className="text-lg font-semibold border-b pb-2">{summary.studentName}</h3>
+          <div className="flex items-center justify-between border-b pb-2">
+            <h3 className="text-lg font-semibold">{summary.studentName}</h3>
+            {/* v4-P1-12: 接入 exportGradesAction，支持按 studentId 导出 */}
+            <ParentExportButton studentId={studentId} studentName={summary.studentName} />
+          </div>
+          {summary.records.length > 0 && (
+            <GradeTrendCard summary={summary} classAverageData={classAverageTrend} />
+          )}
           <StudentGradeSummary summary={summary} />
         </>
       )}